1. Technical Field
The technical field relates to cable assemblies for connecting a plurality of batteries to a load.
2. Background Description
Most batteries installed on internal combustion engine equipped motor vehicles are designed for 12 volt direct current (DC) starter and electrical systems. Heavy duty trucks typically have three or four 12 volt batteries, connected in parallel, to support the cold cranking amperage draw of the starter motor for the vehicle's diesel engine starter. Some heavy duty trucks which use a 24 volt starter system mixed with a 12 volt electrical system in which parallel and series connections are mixed for a set of 12 volt batteries.
Batteries are conventionally connected in parallel by linking like polarity terminals of the battery set using jumper cables. Typically one battery is connected to the next in succession. Battery cables connect the positive and negative terminals of one of the batteries to the load.
A conventional motor vehicle battery for an internal combustion engine equipped vehicle is subjected to its highest loads and highest discharge rate when the vehicle's engine is cranked by a electric starter motor. Rapid discharge of a battery is the likeliest source of internal overheating of a battery, and premature failure of the battery. Experience has shown that in an assembly of parallel connected batteries, the battery having its terminals connected by the battery cables directly to the load is the most likely to fail prematurely, possibly on account of internal overheating. Overheating can stem from a battery carrying a greater part of the starting load, especially during cold cranking of the engine and/or due to more rapid recharging of the battery following starting. Overheating depletes battery cell chemistry and promotes the accumulation of sludge at the bottom of the battery cell closest to the main terminal, potentially shorting out cells within the battery. Excessively quick recharging can reduce water levels in a battery from electrolytic reduction of water into hydrogen and oxygen.
In addition, the jumper cables used to connect the batteries to one another are prone to heat damage adjacent the cable's terminating connectors.
Premature battery failure has been addressed by periodically rearranging the order of the batteries in the connection sequence and changing which battery of the group is the one connected by battery cables to the load without an intervening jumper cable. This action periodically changes which battery is subjected to the stresses imposed by being the battery directly connected to the vehicle electrical system and thus supporting the heaviest loads and seeing the fastest recharging cycles.
Pre-made cable assemblies are known where a butt splice is introduced to the starter cable and an individual cable assembly for each battery provided. The cable assemblies are cut to different discrete lengths to reach a particular battery location. This approach eliminates the use of jumper cables between batteries, however the resistance in the paths from individual batteries still differs from battery to battery stemming from the different lengths of the subsidiary cable assemblies.